### Inplace matrix multiplication in BLAS level 3

Posted:

**Sun Jan 01, 2017 7:22 pm**I have a large B matrix of size 10Million x 1000 and I want to compute the result of its multiplication with a square 1000 by 1000 matrix in place. Currently the level 3 blas provides the *trmm functions which allow us to overwrite the input matrix during multiplication i.e. B := alpha*op( A )*B , where A must be triangular.

but there is no such level 3 functionality when the input matrix is a general square matrix instead of triangular.

Now to do my inplace matrix multiplication, I can either do 10Million level 2 BLAS calls to matrix vector multiplication, or

I can do a LU decomposition of A and then two level 3 BLAS calls to trmm. I was interested in discussing if there was a third solution that I had overlooked.

but there is no such level 3 functionality when the input matrix is a general square matrix instead of triangular.

Now to do my inplace matrix multiplication, I can either do 10Million level 2 BLAS calls to matrix vector multiplication, or

I can do a LU decomposition of A and then two level 3 BLAS calls to trmm. I was interested in discussing if there was a third solution that I had overlooked.